Methylestradiol

Methylestradiol, or 17α-methylestradiol (17α-ME), is a semisynthetic, steroidal estrogen that has been sold in combination with normethandrone (methylestrenolone), an anabolic-androgenic steroid and progestin and , under brand names including Ginecosid, Ginecoside, Mediol, Renodiol for the treatment of menopausal symptoms in Brazil, Venezuela, and Indonesia. Due to the presence of the 17α-methyl group, methylestradiol cannot be deactivated by oxidation of the 17β-hydroxy group, resulting in improved metabolic stability and potency relative to estradiol analogously to ethinylestradiol (17α-ethynylestradiol). In addition to its clinical use, methylestradiol has been studied as a radiopharmaceutical.

Methylestradiol is an active metabolite of the anabolic-androgenic steroids methyltestosterone (17α-methyltestosterone) and metandienone (17α-methyl-δ¹-testosterone) and is responsible for their estrogenic side effects such as gynecomastia (breast development) and fluid retention.